Short story sequel doujinshis of Toshishita Kareshi ni Hirowaremashita:
vol.1: Toshishita no Kuseni Iroiro Sugokute Komarimasu / Despite Him Being Younger, There Are Various Things That I Worry About (2016/10/02)
vol.2: Toshishita Kareshi ga Tamani Kawaikute Komarimasu. / My Younger Boyfriend is Occasionally So Cute it Kills Me (2017/3/20)
vol.3: Anta ga Omou Hodo Otona Janaishi / You're Not As Grown Up As You Think (2018/03/04)
Alternative:
Anta ga Omou Hodo Otona Janaishi; Despite Him Being Younger, There Are Various Things That I Worry About; My Younger Boyfriend is Occasionally So Cute it Kills Me; Toshishita Kareshi ga Tamani Kawaikute Komarimasu.; Toshishita no Kuseni Iroiro Sugokute Komarimasu; You're Not As Grown Up As You Think; アンタが思うほど大人じゃないし; 年下のくせにいろいろすごくて困ります; 年下彼氏がたまにかわいくて困ります。